I'm sure the TP22 will be loud enough to fill the room with some sound with the RB-51s

The RB-51s are rated 50Hz-24KHz ± 3dB, which means you would probably set the crossover on an external sub to somewhere around 50hz to 55hz to integrate the sub (although if you like a different setting, go with that--let your ears be the judge). With the Promedia amp, you aren't going to hear any midbass from those speakers. It's almost all coming from the Promedia sub. I would bet that the RB-51s would have better sounding midbass than that Promedia sub (I used to own the Promedia 2.1).

When you get ready to buy a sub, I recommend researching and asking questions in the AVS budget subwoofer discussion thread. There are people there that know a lot about home audio subs that are constantly watching for best deals.

And I would look for a sub like the Dayton SUB1000 that has high level speaker level inputs AND outputs:

That allows you to run the speaker out from the TP22 to the speaker in on the sub amp, and then the speaker out on the sub amp to the speakers. That's a passthrough connection (the sub isn't powering the speaker; the TP22 would be), and the advantage of it is that you can then set the gain (volume) on the sub to match up with the speakers and use the volume control on the TP22 to adjust the sound. You could get a sub that has left/right RCA inputs only, and split the sound coming from your computer and send it to both the sub and the TP22. Only then you would need to set the volume on the TP22 and the gain on the sub to match for good integration, and from then on use the volume on your computer to control the sound level.

Yea the sub-800/1000/1200 are definitely next on my list of upgrades. just a little strapped for cash atm so im holding off and using my old promedia sub to power the speakers till the tp22 arrives. You think that the rb-51s will sound better without the subwoofer as whole (again in the split connection setup not that speakers coming out of the promedia sub setup)?

Yea the sub-800/1000/1200 are definitely next on my list of upgrades. just a little strapped for cash atm so im holding off and using my old promedia sub to power the speakers till the tp22 arrives. You think that the rb-51s will sound better without the subwoofer as whole (again in the split connection setup not that speakers coming out of the promedia sub setup)?

If you split the connection to the TP22 and the Promedia sub, the Promedia will undoubtedly add some lower frequencies but you will also be double bassing the midbass because of the higher crossover than needed in the Promedia amp. I would listen to just the TP22 and the RB-51 for a week or so to (a) let the RB-51s break in a little bit (you may find that the the bass may open up a little after 10, 20, or 40 hours of use) and (b) to get used to their sound. Then try both together.

That allows you to run the speaker out from the TP22 to the speaker in on the sub amp, and then the speaker out on the sub amp to the speakers. That's a passthrough connection (the sub isn't powering the speaker; the TP22 would be), and the advantage of it is that you can then set the gain (volume) on the sub to match up with the speakers and use the volume control on the TP22 to adjust the sound. You could get a sub that has left/right RCA inputs only, and split the sound coming from your computer and send it to both the sub and the TP22. Only then you would need to set the volume on the TP22 and the gain on the sub to match for good integration, and from then on use the volume on your computer to control the sound level.

Going back to this post, is it bad that I am using speaker inputs vs the line in rca inputs? I think i remember reading somewhere that rca is the preferred input

oh aite sounds good. One last thing (i hope), would anyone here know if getting a asus xonar dg is worth it over my integrated realtek 889? There have mixed reviews online and it seems its mainly if i wanted to use it with headphones which isnt implausible as I would use my dj100s

The Promedia speakers have small 3" drivers. Most likely the amp in the Promedia sub has a built in crossover in the 120hz or higher range to integrate with the sub. Consequently, you are not getting midbass output from your RB 41s with that amp.

I use an Indeed TA2021 amp, equivalent to the Topping TP21. My speakers have a sensitivity rating of 89db 1 watt/1 meter and can hit 100 db from 2.5" to 3" away. Most likely the RB 41s could equal that.

Now if you are expecting loud, room filling sound, you might need to adjust your expectations or adjust your budget. After all, you are looking at amps in the approx. $100 range.
Every amp reaches high distortion as it nears its limits. That distortion rating is to let you know the maximum amount of power you can expect to draw from it before clipping, not what its distortion is at lower volumes.

To go back to ur earlier post, i looked up the crossover of the sub and its not even close to 120hz... its 5khz :x

Alright well due to some mishaps with usps i got the amp on wednesday but I gave the amp a listen for roughly 4 hours last night. To be completely honest I dont like the feel of just 2.0 speakers probably because ive been spoiled by the promedia sub and i like the air brushing against my toes

Anyway, obviously the rb-51 II provide a much fuller sound than the promedia satellite speakers and they are much clearer than the promedias by a long shot. But thanks everyone for the help, I am very pleased with my new speakers, one day ill get a sub to complete them :]